Include <unistd.h> to avoid implicit-function-declaration for close a…

…nd syscall (#2321)

See https://docs.python.org/3.13/whatsnew/3.13.html

"""
Python.h no longer includes the <unistd.h> standard header file. If needed,
it should now be included explicitly.
For example, it provides the functions: read(), write(), close(), isatty(),
lseek(), getpid(), getcwd(), sysconf() and getpagesize().
"""

psutil/_psutil_sunos.c

@@ -51,6 +51,7 @@
 #include <arpa/inet.h>
 #include <net/if.h>
 #include <math.h> // fabs()
+#include <unistd.h>
 
 #include "_psutil_common.h"
 #include "_psutil_posix.h"

psutil/arch/linux/net.c

@@ -10,6 +10,7 @@
 #include <sys/ioctl.h>
 #include <linux/if.h>
 #include <linux/version.h>
+#include <unistd.h>
 
 // see: https://github.com/giampaolo/psutil/issues/659
 #ifdef PSUTIL_ETHTOOL_MISSING_TYPES

psutil/arch/linux/proc.c

@@ -7,6 +7,7 @@
 #include <Python.h>
 #include <sys/syscall.h>
 #include <sched.h>
+#include <unistd.h>
 
 #include "proc.h"
 #include "../../_psutil_common.h"

psutil/arch/solaris/environ.c

@@ -19,6 +19,7 @@
 #include <sys/procfs.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <unistd.h>
 
 #include "environ.h"